Drawing press



March 5, 1940. STACY 2,192,778

DRAWING PRES 5 Filed Nov. 5, 1955 3 Sheets-Sheet l A TTOEA/EY5.

March 5, 1940. T. F. STACY 2,192,773

DRAWING PRESS Filed Nov. 5, 1935 3 Sheets-Sheet 2 March 5, 1940. STACY2,192,778

DRAWING PRESS Filed Nov. 5, 1935 3 Sheets-Sheet 5 M m #2 W VAR/ABLEDEL/VERY PUMPS.

5/ QC4LWMZMM A TTORA E Yd.

Patented Mar. 5, 1940 UNITED STATES PATENT OFFICE DRAWING PRESSApplication November 5, 1935, Serial No. 48,382

19 Claims.

This invention relates to metal drawing presses in which a blank sheetof metal is drawn and deformed into a desired form or configuration. Inthe drawing of sheet metal from blanks, when deep draws are made, acertain point is sometimes reached at which the metal will tear orrupture. If the speed of drawing is too great, there is further dangerof tearing of the metal blank.

An object of the invention is to provide an improved method of drawingmetal from blanks,

with which exceptionally deep draws will be possible; and with whichlosses from tearing and rupturing of the metal blanks will be reduced.

Another object of the invention is to provide improved means forcontrolling and varying the pressure on a metal blank during the drawingoperation.

Another object of the invention is to provide an improved metal drawingpress and control means therefor, with which deeper draws may be madewith a minimum of loss from tearing and rupturing of the blanks in thedrawing operation; with which the speed of the draw need not beobjectionably lessened; and which will be rela tively simple,dependable, easily controlled, compact and inexpensive.

A further object is to provide improved means for controlling the speedof travel of a platen in accordance with a predetermined plan.

Various other objects and advantages will appear from the followingdescription of an embodiment of the invention, and the novel featureswill be particularly pointed out hereinafter in connection with theappended claims.

In the accompanying drawings:

Fig. l is a diagram of a drawing apparatus and control systemconstructed in accordance with this invention;

Fig. 2 is an elevation of part of the control mechanism for one of theparts;

Fig. 3 is a transverse sectional elevation through a pilot operatedcheck valve, two of which are employed in the system shown in Fig. 1;

Fig. 4 is a sectional elevation through a control valve which may beused in the system of Fig. 1 for controlling the rate of travel of themain ram;

Fig. 5 is a sectional elevation through another control valve which maybe used for maintaining a sustained pressure on the blank holding ringin the system of Fig. 1;

Figs. 6 and '7 are sectional elevations of a control valve used. in thesystem of Fig. 1 for controlling the activity of the auxiliary blankholding rams;

Figs. 8 and 9 are similar elevations of valve mechanism used in thesystem of Fig. 1 for controlling the activity of the main ram, and

Fig. 10 is a diagram similar to Fig. l but illustrating somemodifications in the system.

While many features of the invention may be applied to presses ofvarious types, including mechanical, crank and hydraulic presses, orcombinations of them, the improved system is shown, by way of example,as utilized in connection with a hydraulic press having upon its base arelatively fixed die element ill with a suitable die cavity or recess Hin its upper face. Supported above the base, as usual in hydraulicpresses, is a platen f2 which is guided in the usual manner forreciprocation toward and from the base which mounts the die element Hi.This platen i2 is operated in both directions by a piston l3 projectinginto a main cylinder id and forming therewith a double acting main ram,by which the platen if: is reciprocated in opposite directions. Theplaten i2 removably mounts a die element it which cooperates with thedie cavity H to draw and deform a metal blank 15 into a desiredconfiguration or shape.

The blank it is placed on the die element Ii] across the cavity H, andwhile it is confined in that position, the cooperating die element l5,

during the downward travel of the platen 12, Jill draw and deform theblank until it conforms to the shape of the cavity H. During the drawingoperation it is desirable that the periphery of the blank be held undera sustained pressure in order to prevent wrinkling of the blank whilebeing drawn. For this purpose a blank holding ring or member H isdisposed beneath the platen l2 and is provided with an aperture oropening 18 through which the die element 95 projects. The ring or memberii is supported by a plurality of pistons 59, which extend upwardlytherefrom through apertures 2!! in the platen l2, and into auxiliarycylinders 21 so as to form with the cylinders 2!, double acting ramsthat support and reciprocate the blank holding ring or member ll.

When the pistons 19 are lowered or forced downwardly, the member or ringI? will engage with the blank l6 and confine it against the die element10 with a sustained pressure. The details of such drawing presses arewell known in the art, and in themselves form no part of the invention,and while the blank holding means may be employed equally well with amechanical all) or any other type of drawing press, the means forcontrolling the pressure of the blank holding ring onthe blank isparticularly adaptable for use in connection with a hydraulic press inwhich the drawing platen is reciprocated by hydraulic rather thanmechanical means.

The activity of the auxiliary ram pistons i9 is controlled by a valve 22illustrated in Figs. 1, 6 and 7, and the activity of the main ram pistonI3 is controlled by a valve .23 which is similar in construction to thevalve 22. The valve 22 is provided with a valve chamber i l in which aspool-shaped valve element 25 reciprocates, and reciprocation of theelement 25 is obtained by a valve stem 26 extending from the element 25downwardly through the bottom end of the easing of valve 22, anddownwardly through a passage El provided in a lateral extension of theblank holding ring or member IT. The lower end of the stem 25 ispivotally connected to one end of a control lever 28, which is pivotedat 2Q on a suitable part of the press frame. Intermediate of its endsand above the ring ll, the stem 26 carries a collar 39 which isshiftable along the stern it into diiierent, desired, adjusted positionsin any of which positions it may be secured in any suitable manner suchas by a set screw. 1

In the particular illustrated example, the stem 26 also extends looselythrough an aperture 3! in the platen l2. The neutral or intermediateposition of the valve element 25 is shown in Fig. l, and the otheroperative positions are shown in Figs. 6 and '1, the element 25 beingshiftable into the different positions by the control lever 28 and thecollar 30. The liquid for the actuation of the auxiliary rains thatcontrol the blank holding ring ll may be obtained from any suitablesource such as a tank 32 of any desired size, and preferably, althoughnot essentially, the liquid in tank 32 is maintained under a pressuresuch as under a pneumatic pressure, or by the use of an accumulator, notshown. Various means for malntaining the liquid in the tank 32 undersuch pressure are well known and are omitted in the interest of clarity.

A unidirectional, continuously operating pump 33 is connected at itsintake side by a pipe 34 to one portion of the tank 32, and at itsoutlet side is connected by a pipe 35 to a port 35 in the valve chamber25: approximately midway between its ends and between the flanges 31 and38 of the spool-shaped valve element 25. One end of the chamber TM isconnected by pipes 33 and All to another part of the tank 32, and theopposite end of the chamber 24 is similarly connected by pipes M and 2to the pipe 45 which leads to the tank 32.

When the valve element 25 is in a neutral or intermediate position, suchas shown in Fig. l, the flange 3'! of one end of the spool, bridges andcloses an annular port 43 in the side wall of the chamber 2t, and thisport 43 is connected by a branched pipe 3 3 to the lower or pullbackends of the auxiliary cylinders 2!, that is to the ends of the cylinders25 which are beneath the head of the piston 19. Any number of thecylinders 2| may be employed, but only two are shown for the sake ofsimplicity.

The opposite ends of the cylinders 2!, that is, the upper ends whichextend across the entire end areas of the heads of the pistons iii, areconnected by a pipe 55 with a port G6 which is aligned with the otherflange 33 of the spool of the valve element 25, when the latter is inthis intermediate or neutral position shown in Fig. 1. The flange 38,however, instead of bridging and closing the port t6, when alignedtherewith, in the manner that the flange 37 closes the port Q3, isbevelled or chamfered on" on opposite sides of its peripheral edge sothat when this flange 3? is aligned with this port 56, as shown'in Fig.1, liquid in the chamber 25 may pass around the flange 33 as well asthrough the port 56. which, for convenience, is made annular.

When the valve element 25 is shifted into the position shown in Fig. 6,that is, when it is moved upwardly from the neutral position, such asoccurs when the free end of the control lever 23 is depressed, theintermediate port 33 will be connected through the central annular spacesurrounding the valve element with the upper port ill, and at the sametime the flange 31 has uncovered the port 3 so that communication isestablished between pipe ll leading to the lower end of the chamber 2 3and the port 43. When the valve element 25 is in this upper positionshown in Fig. 6, any liquid trapped in the auxiliary cylinders 25 belowthe heads of the piston, may escape through the pipe l l, port 43, thelower end of chamber 2 5 and pipes ll and 42, back to the tank 32. Atthe same time the pump 33 withdrawing liquid from the tank 32 throughthe pipe 3 and delivering it through the pipe 35, port central portionof the valve chamber 2%, port and the pipe 35 to the upper ends of theauxiliary cylinders i l.

The pistons 53 are now free to descend and the liquid delivered from thepump into the upper ie cylinders El will urge the pistons l3 5 ends ofdownwai ly. Until resistance is encountered, however, by the ring ll,its weight will tend to pull the pistons is downwardly, and in order toexpedite this movement, a prefill check valve N is connected at one sidethrough a pipe 48 to the pipe and at its other side by a pipe l9 to thepipe One type of such a check valve is shown in Fig. 3. The free checkvalve element 59 provided in this valve l'l, opens freely to pass fluidfrom the pipe as to the pipe is and automatically closes to preventreverse flow. Thus as the pistons it start downwardly to place the blankholding ring ii on the blank it, the operating liquid will flow from thetank J2 through pipes M and lil to the valve ll, will open the checkvalve 53 and pass through the pipes 58 and 45 to the free ends of thecylinders 21 to ill the space created by descending pistons 59. When theauxiliary pistons iii are who raised, it is desirable to open the valvell and allow the liquid displaced from the upper ends of the cylinders2i by the pistons It to return easily and rapidly to the tank 32. Forthis purpose a pilot cylinder Ma (Fig. 3), operates a piston ll'bagainst the action of a helical compression spring Me to lift the valveelement 53 forcibly. A branch of the pipe M is connected to the pilotcylinder ilo. Hence, whenever operating liquid is supplied to the lowerends of the cylinders ill to lift the pistons 13, the same operatingliquid pressure is applied to the pilot device to lift valve element 58and allow free return of liquid from the upper ends of cylinders 2| totank 32, without passage of all or the displaced liquid through thevalve 22.

When the blank holding ring ll engages with the blank 53, resistance isimmediately offered to further downward travel of the pistons l 9,whereupon the pressure in the upper ends of the cylinders 2! immediatelybuilds up because of the continued delivery thereto of the operatingliquid from the pump 33, and this increased pressure ,with the teeth ofa rack bar 6!.

.' platen tends to cause a reverse flow through the valve 47. The valve4? thereupon automatically closes through the seating of its valveelement 50, and thereafter continued delivery of the operating liquidfrom the pump 33 to the upper ends of the cylinders 2i will cause thebuilding up of a high pressure on the pistons 19 acting in a downwarddirection, which pressure is transmitted to the blank holding ring l?and thus to the periphery of the blank 16.

It is desirable to maintain a sustained pressure on the ring l? in thisholding position, and this is accomplished in accordance with thisinvention by means in addition to the pump 33. For this purpose the port45 is also connected by a pipe 5! through a valve seat to the valvechamber 52 of a pressure relief valve 53. This pressure relief valve,shown particularly in Fig. 5, has a free valve element 54 which is urgedinto closed position against its seat by a spring 55 which is compressedbetween the valve element 54 and a pressure head 55 also disposed in thechamber 52. The pressure head 56 is mounted on a stem 5'! which hasthreaded engagement with the casing of valve 53, so that when this stemor rod 5? is turned or rotated, it will be shifted endwise in thechamber 52 in a direction depending upon the direction of rotation ofthe stem. The pressure of the spring 55 on the valve element 54 willthus be varied by rotation of the stem or rod 5'1.

An outlet 58 of the chamber 52 is connected by a pipe 59 to the pipe #2,so that when the pressure in the pipe 5|, which is at all times incommunication with the upper ends of the auxiliary cylinders 2i, becomessufficient to overcome the pressure of the spring 55 on the valveelement 56, the valve element 54 will open and liquid will pass throughpipes 59 and 12 back to the tank 32. As soon as the excess pressurefalls the spring 55 will again close the valve element 5d, and hence thepressure in the upper ends of the cylinders 25 and thus on the blankholding ring I 7 will be sustained, and will be directly proportional tothe pressure of the spring 55 on the valve element 54. Thus the pressureon the ring 11 may be varied by rotating the stem or rod 51 in onedirection or the other, depending upon whether an increase or decreasein the pressure of the ring I! on the blank i6 is desired.

In order to vary the pressure on the spring 55 and thus the pressure ofthe ring H on the blank Hi, the outwardly extending end of the rod orstem 57 is provided with a pinion 69 which meshes The bar 6| is rockablyconnected at its lower end to one arm of the bell crank lever 62,pivoted at 83, and mounts upon its other arm a cam follower or roller Aspring urges the bell crank lever 82 yieldingly in a direction to forcethe cam follower B l against a cam surface 66 which is carried by theplaten I2.

As the platen l2 moves toward the die element 10. the undulations of thecam surface cause a rocking of the bell crank lever 62, reciprocation ofthe rack bar 61, and rotation of the pinion 60 and of the stem or rod57, to change the pressure on the blank holding ring l? in accordancewith a predetermined plan under the control of the 12. Thus while thering 1! remains clamped against the blank it under a sustained hydraulicpressure, the travel of the platen in a downward direction will cause avariation in this sustained presstue in accordance with a predeterminedplan.

The connection between the rack bar El and the bell crank lever 62 isone which causes the rack bar to reciprocate vertically in bothdirections upon rocking of the bell crank lever 62. For example, therack bar may have a shoulder or collar 6'! provided thereon at a shortdistance from the lower end of the bar and engaging with one side of thebell crank arm, and the bar, after passing loosely through an apertureor slot in the arm of the bell crank lever 62, carries a washer B8 and anut 63. The collar 6'! and the washer 88 have semi-spherical or convexarcuate surfaces abutting opposite faces of the bell crank lever 62, sothat the rack bar may rock laterally somewhat at its connection to thebell crank 82.

The valve 23 is similar in construction to the valve 22, and is providedwith a central annular port I'll and intermediate ports H and 72. Thevalve element 13 is of spool shape, similar to the valve element 25 ofvalve 22, and has the flange 14 at one end, which corresponds to theflange 41 of valve 22, of such thickness that when in its neutralposition shown in Fig. 1, it will bridge and close the port ii. Theother flange 75, which corresponds to the flange 38 of valve 22, isbevelled or chamfered on both faces at its periphery for a similarpurpose, so that when the valve element 13 is in a neutral orintermediate position, such as shown in Fig. l, in which the flange l4closes the port H, the chamfered flange '15 will be aligned with theport 72. Liquid may thus pass from the port 10 around the flange at theport '12, through the upper end of the valve chamber It, and thencethrough the pipe 38 to the tank 32.

A unidirectional, continuously operating pump ll is connected at itsintake side by a pipe 78 to a portion of the tank at a point spaced fromthe connection of the pipe 483 to the tank. The output or delivery sideof the pump 7? is connected by a pipe '19 to the port Hi, so that whenthe valve element 13 is in the neutral position shown in Fig. 1, theliquid delivered by the pump 19 will flow around the periphery of flangel5 and back through the pipe 49 to the tank, thus circulating idlythrough the valve chamber '55. The port ii is connected by a pipe 83 tothe lower end of the main cylinder 14, and thus liquid trapped in thecylinder M, below the head thereof, cannot escape through the port 7 l.which holds the platen l2 in raised position.

Pipe 48 is also connected by a branch pipe 81 to the lower end of thechamber 13 for a purpose which will appear presently. The valve element73 is reciprocated endwise in the chamber '16 by means of a valve rod 82which extends downwardly through the lower end of the chamber 76, passesthrough an aperture 83 in the platen l2, and at its lower end ispivotally connected by a pin 84 to one end of a control lever which inturn is pivoted at 88 to a suitable support.

When a downward movement of the platen is desired the operator pushesthe free end of the control lever 35 downwardly, which elevates the rod82 and through it shifts the valve element '13 from the neutralintermediate position shown in Fig. 1 to the upper position shown inWhen this occurs the flange l4 uncovers the port H and positivelyprevents communication between the ports '18 and H. Communication is,however, established between the pipes 36 and BI so that the fluidtrapped in the lower end of the main ram cylinder l4 may escape throughthe pipe 80, the port H, the chamber '16, and pipes 81 and 40 back tothe tank 32.

f of the chamber 92.

At the same time the flange it moves above the port '12 andthe liquiddelivered by the pump 17 instead of passing upwardly and around theflange its to the pipe 48 will be compelled to pass through the port l2,and thence by means of pipes 81 and 68 to the upper end of the maincylinder it. The movement of operating fluid into the upper end of thecylinder i i and the weight of the platen I2 will cause the platen todescend as rapidly as fluid can enter the upper end of the cylinder M.

In order that the speed of the platen 52 may be rapid until the drawingoperation starts, the pipe 88 is connectedthrough a prefill check valve89 to the pipe lll and thus to the tank This valve Sl is identical with,except usually larger than, the valve 47 shown in 3 and it opens freelyin a direction to pass fluid from the pipe ii to the pipe 88 and themain cylinder 2 so that as the descent of the platen creates a suctionin the upper end of the cylinder operating liquid may flow from the tank32 through the pipe Mi, the valve 89 and pipe 88 into the upper end ofthe cylinder is, thus supplementing the liquidvdelivered by the pump iito the upper end of the cylinder M.

When the die it carried by the platen E2 engages with the blank 5,pressure resistance to further movement of the platen i2 is set up, andsince the pump l'i continues to deliver liquid to the upper end of thecylinder i l, the pressure on the upper end of the piston is will buildup, whereupon the liquid in the cylinder is will tend to flow outwardlythrough the pipe 83 and valve 89 to the pipe id, but thereupon the valve89 closes automatically, so that the pressure on the upper end ofthepiston l3 builds up in response to the continued delivery of liquidto the upper end of the cylinder i l from the pump ll.

It is desirable to vary the speed of downward travel of the platenduring the drawing operation on the blank l6, and the means for varyingthis speed in accordance with a predetermined plan will next bedescribed. The pipe 92] connects the pipe 31, leading from the port 12,to one end of a bypass valve 9! which is shown diagrammatically in Fig.l and in greater detail in Fig. In the chamber 92 of the valve 9i is avalve element 93 which is mounted on the end of stem or rod M. The rod 9has threaded engagement with the inner end of a sleeve that closes oneend Thus as the stem Qt is rotated, it will be threaded into and out ofthe chamber 92 to various extents, so as to shift the valve element t3toward or from its valve seat in the chamber 92, depending upon thedirection of rotation of the stem t l.

A pipe 96 connects the chamber $2 to the pipe til, from which it will beobserved that a portion of the liquid delivered by the pump ll to thepipe 8'! may pass through the pipe tit and the valve 9i back to the pipeit, thus completing an idle circuit through the pump for a portion ofthe liquid. The proportion of the liquid which is bypassed through thevalve st in this manner will vary with the setting of the valve elementand this setting may be varied by rotating the stem or rod 9% in onedirection or the other, deending upon whether an increase or decrease inthe amount of bypass is desired. The outer end of the stem or rod 94 isprovided with a pinion 9! which meshes with the teeth of a rack Q8. Thisrack bar depends from the pinion er and at its lower end is rockablyconnected to one arm of a bell crank lever 99, such as the mannerexplained for the connection of the rack bar 6| to the bell crank lever52.

The bell crank lever 99 is pivoted at Mill, and its other arm carries anoffset cam roller or 01- lower it! which engages with and rolls upon acam surface 502 carried by the platen 12. A spring i833 that isconnected to the horizontal arm of the bell crank 53B, urges the latterin a direction to press the roller illl against the undulating camsurface 592 at all times. The cam surface it? extends or undulates inthe direction or" the travel of the platen, and thus as the platen i2descends, the cam surface H32 thereof will cause a rocking of the bellcrank 95 and through the resulting reciprocation of the rack bar 98,

the pinion 9'? and stem S t will be turned in one direction or the otherto increase or decrease the amount of liquid bypassed. When more liquidis bypassed, the speed of travel of the platen l2 will be decreased, andvice versa.

Thus the platen 52 in its movement controls its own speed during thedrawing stroke, and by selecting the undulations. of the cam surfaceI02, the speed of travel of the platen l2 may be decreased at thosepoints or zones in the drawing operation, where there is danger oftearing or rupturing of the blank, with the result that deeper draws maybe successfully made. By selecting the character of the cam surface lit,the pressure or the blank holding ring H on the periphery of the blankit may be decreased to the extent desired in the proper zone of theplaten travel to allow more slippage of the blank It at the criticalzones, which in some cases may be at the same time that the speed of theplaten i2 is decreased. Any other control of the pressure of the blankholding ring on the blank or in the speed of the platen may be obtainedmerely by proper selection of the shapes of the cams 66 and i112.

At the end of a drawing operation the operator elevates the upper end ofthe control lever 85, which pulls the valve rod 32 downwardly and movesthe valve element 73 from the position shown in Fig. 8 to the positionshown in Fig. 9. When this occurs the flange is will out chcommunication between the ports l and '52, thus interrupting deliveryfrom the pump ll to the upper end of the main cylinder M, and the flange'Hl will move concomitantly to a position between the port it and theoutlet pipe Bl, so that escape of further liquid from the lower end ofthe cylinder i l will be prevented. The central port it is now connectedto the port i l, and thus the liquid delivered by the pump ll to thevalve chamber it will now pass through the port ii to the pipe 88, andthence to the lower end of the cylinder 14, so as. to exert a liftingpressure on the piston l3. The flange 15 has moved from a position inwhich it interrupted communication between the port 52' andthe pipe sothat the liquid previously delivered to the upper end of the cylinder 13 may now pass through the ipes 88 and 3'2, the port 72 and the pipe itback to the tank 322. The pressure in the upper end of the cylinder i lthus immediately falls and permits an upward movement of the piston 13.

In order to expedite the upward movement of the platen l2, provision ismade for forcibly opening the check valve of the prefill valve 39. Forthis purpose a branch pipe i04- leads from the pipe 89 to the pilotcylinder of the prefill valve 8? so as to forcibly open the check valveelement 51! thereof in the manner hereinbefore explained in con-fnection with the opening of the preiill valvev 47.

As the platen l2 moves upwardly and approaches its upper limit ofmovement, it will engage with a collar it??? provided on the valve rod82, so that further upward movement of the platen l2 will elevate therod 82 and shift the valve element (3 from the position shown in Fig. 9to the neutral or idle position shown in Fig. 1. When the valve element73 moves back into this neutral position, the flange M again bridges theport I! and thus disconnects the pump 7'! from the pipe 3%, and alsoprevents escape of liquid from the pipe 8!], thus locking the mainpiston l3 in its elevated position. The flange T at the same time openscommunication from the port to the port l2 and the pipe All, thusconducting the liquid delivered by the pump 7! back to the tank 32. Thisidle circulation of liquid through the pump ll will continue and thepiston !3 will be effectively held in its elevated position. The collarM95 is mounted on the rod 82 for adjustment endwise along it, and it maybe secured in different adjusted positions in any suitable manner suchas by a set screw which is carried by the collar and is engageable withthe rod 82.

When the platen Ill starts upwardly the blank holding ring I! willcontinue to hold the blank It against the die element l9, so as to stripthe formed blank from the die element l5, and after that occurs theoperator elevates the free end of the control lever 28 which shifts thevalve element 25 from the position shown in Fig. 6 to the position shownin Fig. 7. When this occurs, the intermediate port 36 to which the pumpdelivers operating liquid will be connected with the port 43, and thusthe liquid from the pump will be delivered through the pipe 44 to thelower ends of the auxiliary cylinders 2 l. At this time the flange 38 isdisposed between the ports 36 and 4E and shuts oil communication betweenthem, but places the port it in communication with the pipes 39 and 48.

The liquid in the upper ends of the auxiliary cylinders 25 may then passthrough the pipe 45, through the port and pipes 39 and All back to thetank 32, and thus as the liquid is delivered under pressure to the lowerends of the auxiliary cylinders the auxiliary pistons lo will beelevated and thus will elevate the blank holding ring or element ll andrelease the blank IS.

The pressure of the liquid from the pump 33 is transmitted through thepipe to the pilot cylinder filo. and will force the pilot piston ill)upwardly against the action of the spring 470. This forcibly opens orlifts the check valve element 5! so to allow the liquid to pass directlyfrom the upper ends of the auxiliary cylinders 13! to the pipe Ml andback to the tank. After the blank holding ring ll has been elevated, theformed blank l3 may then be ejected from the die recess il in anysuitable manner which is common in the art, such as by a spring ejectoror air or hydraulic mechanism, not shown, and which in itself forms nopart of this invention.

As the ring ll approaches its upper limit of movement it engages thecollar shifts the valve stem or rod 2 3 upwardly, and thus returns thevalve element 25 from the Fig. '7 position to the Fig. 1 position whichis the idle or neutral position occupied when the press is idle. At thistime the pump 33 circulates liquid idly through the valve 22 and pipes39 and 4G back to the tank 32, and the pistons l S are held in theirupper positions by the liquid trapped in the lower portions of theauxiliary cylinders 2!. due to the bridging of the port 43 by the flange31 of the valve element 25.

The operation of the press and system will be clear from the foregoingdescription, but may be briefly summarized as follows:

Assuming that the parts are in the idle position shown in Fig. 1, let itbe assumed that a blank 18 has been placed on the die element H] acrossthe die recess H. The operator then depresses the free end of thecontrol. lever 28, which elevates the valve element 25 an initiates adownward movement of the auxiliary pistons I9 and ring l1. At the startof this downward movement of ring ll, the pressure on the pipe 44 isreleased, and thus the pressure on the pilot piston 41b is decreased,whereupon the spring 470 forces the pilot piston no downwardly torelease the check valve element Ell, and permit it to close. When thering I! engages with the blank iii, the pressure then built up in theupper ends of cylinders 2i causes the prefill valve ll to close, and thecontinued delivery of liquid from the pump 33 to the upper ends of theauxiliary cylinders 2! will build up a sustained pressure upon the blankholding ring '5, until the pressure is suificient to overcome the forceof spring 55. whereupon the valve element 54 opens sufficiently tomaintain the pressure at that determined by the setting of the pressurehead 56.

When the blank holding ring has progressed far enough so that it willengage and hold the blank 96 before the platen !2 can carry the dieelement into engagement with the blank, the operator depresses the fr eend of the control lever which elevates the valve element 13 from theFig. 1 position to the Fig. 8 position, and initiates a downward movemnt of platen l2. The downward movement of the platen l2 will becontrolled at intervals in its descent as to speed by the cam surfaceH32 and the bypass valve 9!, the latter being set into difierent degreesof open ing by successive changes in the character of the surface 62 asthe platen l2 descends. At the same time the pressure on the blankholding ring will vary in accordance with the successive positions ofthe platen l2 under the control of the cam surface 56.

At the end of the drawing operation, the opera tor elevates the free endof the control lever 85 and initiates an upward travel of the platen I2that is terminated automatically by engagement of the platen with thecollar 35, through which the rod 52 is elevated to return the valveelement it to the neutral position shown in Fig. l. The upward movementof the blank holding ring I! is initiated after the platen 12 hasstarted upwardly, by tilting upwardly the free end of the control lever23, and the upward movement of the ring H is terminated when it engagesthe collar and elevates the rod 26 sufficiently to return the valveelement 25 to the neutral position shown in Fig. 1.

The shape and configuration of the cam surfaces 55 and H12 will varywith different dies employed, because the slippage and speed of travelmust be varied at just the critical points in the drawing operation.These critical points will vary with different types of blanks beingdrawn and difierent dies that are used, and must be determined for eachdifferent die or blank employed.

In Fig. 10 a slight modification of the controls of the pressure on theblank and of the travel of the platen have been illustrated with so muchof the remainder of the press and system as is necessary to show therelation of the modified parts to the other parts. In this modificationof Fig. 10, the pressure opened valve 53 and the pipes El and 59 shownin Fig. 1 are omitted, and the pump 33 is replaced by a pump H35 whichis of the variable delivery reversible type, but continuously operating.Such pumps are well known in the art and by way of example, one of thisgeneral type is illustrated in U. S. patent to Landenberger et al.411,863,448 issued June 14, 1.932. The pump at its intake side isconnected by the pipe 34 to the tank or source 32 of operating liquid,and its output side is connected by the pipe 35 to the valve 22, as inFig. 1.

The pump I05 is adjustable in order to vary its delivery or to reverseits delivery by means of a yoke I05 which is shifted in alternatedirections by a lever IIl'I pivoted at I518. The lever II): is pivotedto a block I03 which is mounted on a rod I I I) to slide in a directionendwise ther on. A nut or collar III is provided on an end of the rod IIf) so as to limit movement of the rod HE! through the block H39 in onedirection, and a helical spring I !2, disposed on the rod IIB and actingagainst a washer or collar HS that is slidably mounted on the rod I Iii,forces the block H19 yieldingly against the nut or collar lII. Pressureis provided on the spring I I2 by a washer I I4 which is slidable on therod I It and abuts endwise against a pinion H5 that is threaded on therod III). Thus, by rotating the pinion H5, it will be threaded along therod IIFJ so as to further compress or release the spring H2, and thusvary the pressure with which the lever I0! is held against the collar ornut II I.

A lever H6, pivotally mounted at II 1, is pivoted at one end by a pinIIB to a block H9 that is also threaded or fixed on the rod Ht. so thatthe rod I Ill may be forcibly operated in alternate directions to changethe direction of delivery of the pump, or the rate of delivery, in amanner which is well known in the variable delivery reversible type ofpumps. The pressure in the pipe 35, which is the output side of the pumpas connected, is operable upon the lever it? through a small ram, notshown, but which is common in this type of pump, in a manner to rock thelever H31 clockwise in Fig, 10, against the action of the spring I22,while the rod H9 remains in set position. Thus, when the pressure'inpipe 35 equals or exceeds a predetermined pressure, determined by thepressure of spring 1 I2, the lever an will be rocked clockwise in Fig.10 against the action of spring IIZ so as to shift the yoke I96 in adirection to set the pump for neutral delivery position.

If the pressure falls, the spring I I?! will return the lever I0! andyoke I 36 to delivery position,

and the pressure in pipe 35 will built up until it is again suihcient toovercome the pressure on spring M2. By rotating the pinion H5, one maytherefore determine the pressure which will be maintained automaticallyin the pipe 35, and this pressure may be varied merely by rotating thepinion H5 in one direction or other, depending upon whether an increaseor decrease of pressure is desired. The pinion II? meshes with the rackbar Ii! corresponding to the rack bar 5! of Fig. 1, and thus, as theplaten I2 moves downwardly the cam surface 65 will operate the rack barEI to change the pressure on the spring H2 in accordance with apredetermined plan and controlled by the travel of the platen, therebydetermining the pressure on the blank during the drawing operation,which pressure varies with the different positions of the platen inaccordance with a predetermined plan. The lever H6 is operated merely tochange the maximum rate of delivery of the pump, and the reversingfeature of the pump need not be utilized. In controlling the rate oftravel of the plate in the working stroke under the system as modifiedin Fig. 10, the valve SI and pipes 98 and 96 of Fig. 1 may be omitted,and the pump ll of Fig. 1 is replaced by a pump I20 of the variabledelivery reversible type in Fig. 10. The reversible feature need not beutilized in the system. The intake side of the pump is connected to thepipe I8, as in Fig. 1, and the output side of pump is connected by thepipe IS to the valve also as in Fig. 1. The pump I29 is identical withthe pump I05 except that instead of the pinion H5 in the control for thepump Hi5, I have substituted a hand wheel I2I which is threaded on therod l H] for varying the pressure on the spring H2. The rod III) whichvaries the rate of delivery of the pump is connected to a lever I22which corresponds to the lever H6 of the pump I 55 except that the leverIE2 is a bell crank lever and is pivotally connected by a pin I23 to oneend of a link I24 which corresponds to the rack bar 88 of Fig. 1. Thus,as the platen l2 moves downwardly, the cam surface I 02 thereof will actthrough the roller IUI and link I24 to shift the rod III! endwise andthus change the rate of delivery lustrated in order to explain thenature of the invention, may be made by those skilled in the art withinthe principle and scope of the invention as expressed in the appendedclaims.

I claim as my invention:

1.111 a drawing press, a fixed die holding element, a platen mounted formovement toward and from said element, means for actuating said platentoward and from said element, a blank holding member also movable towardand from said element entirely separately from the 1novement of saidplaten, hydraulic means for actuating said holding member toward andfrom said element and for holding it under pressure against saidelement, and means controlled by the platen forpartiallybut not fullyreleasing the liquid pressure of said hydraulic means on said member andthus the pressure of said member against said element, automaticallyduring a predetermined critical interval of the drawing operation duringthe travel of said platen toward-s said element, so as to allowregulated slippage of the blank during said critical interval.

2. In a drawing press, a fixed die holding element, a platen mounted formovement toward and from said element, means for actuating said platentoward and from said element, a blank holding member also movableentirely separately from said platen toward and from said element,hydraulic means for actuating said holding 111cm. ber separately fromsaid platen toward and from said element and for holding it underpressure against said element, a source of actuating liquid underpressure connected to said hydraulic means to operate it, an adjustableregulator for controlling the pressure of said member said element bycontrolling the admission of liquid under pressure to said means fromsaid source, mechanism operated by said platen during its travel towardssaid element for adjusting said regulator to vary the pressure of saidmemher on said element in accordance with a predetermined plan under thecontrol of said platen.

3. In a drawing press, a fixed die holding element, a platen mounted formovement toward and from said element, means for actuating said platentoward and from said element, a blank holding member also movable towardand from said element entirely separately from the platen, fluidactuated means for actuating said member against said element andholding it thereagainst during the travel of said platen while incontact with a blank being operated upon, a source of fluid underpressure connected to said actuated means for moving it and holding itin clamping position, and means controlled by said platen during itstravel towards said element for varying the passage of actuating fluidbetween said source and said actuated means and thereby decreasing andincreasing the pressure of said fluid actuated means on said member inaccordance with a predetermined plan and dependent upon the successivepositions of said platen.

4. In a drawing press, a fixed die holding element, a platen mounted formovement toward and from said element, means for actuating said platentoward and from said element, a blank holding member also movable towardand from said element, hydraulic means for actuating holding membertoward and from said element and for holding it under pressure againstsaid element during travel or" said platen, a source or" fluid underpressure connected to said hydraulic means for operating said holdingmeans in both directions, and for providing the holding pressure, a campart and a follower part, one of said parts being mounted on the platen.for travel therewith and the other part being operated thereby, andmeans controlled by said operated part for varying the passage ofactuating liquid between said source and said hydraulic means andthereby regulat ng the pressure on said member in accordance with apredetermined plan dependent upon the successive positions of saidplaten in its travel towards said element.

5 In a drawing press, a fixed die holding element, a die-mounting platenmounted for movement toward and from element, fluid actuated means formoving said platen toward and from said element, means controlled bysaid platen in its travel towards said element for selectivelycontrolling said fluid actuated means and varying the rate of travel ofsaid platen in accordance with a predetermined plan, a blank holdingmember for holding a blank against said fixed element, and means alsocontrolled by said platen for varying the pressure of said memberagainst said element in accordance with a me determined plan dependentupon the successive positions of said platen.

6. In a drawing press, a fixed die carrying element, a mounting platenmounted for movement toward and from said element, fluid actuated meansfor moving said platen toward and from said el ment, pumping means fordelivering an operatin fluid to said means including a fluid bypasscontrolled by said platen in its travel towards said element forbypassing portions of the operating fluid delivered to said actuatedmeans around said actuated means in different proportions determined bythe successive positions of said platen, for varying the rate of travelof said platen towards said element in accordance with a predeterminedplan dependent upon the successive positions of the platen.

7. In a drawing press, a die-mounting, fixed element, a die-mountingplaten mounted for movement toward and from said element, a fluidoperated device for moving said platen in alternate directions towardsand from said element, a fluid circuit including a pump connected tosaid device for operating said platen in opposite direcions, controllingmeans for said circuit for regulating the direction of travel of saidplaten, and means including a fluid bypass for said circuit from saidpump past said device and operable automatically during the travel ofsaid platen towards said element and controlled by the platen forbypassing varying proportions of the fluid delivered to said device,past said device, and thus varying the speed of travel of said platen indifferent successive zones of its travel in accordance with differentsuccessive positions of said platen.

8. In a drawing press, a fixed die holding element, a platen r ountedfor movement toward and from said element, ram means connected to saidplaten for operating it toward and from said element, a source ofactuating fluid, a continuously operating pump, a ci cuit including saidsource, pump and said ram means for causoperation of said ram means inone direction or the other, a bypass forming a part of said circuit andoperable to bypass a portion of said actuating fluid around said rammeans while said ram means is operating the platen towards said fixedelement, and means controlled by said platen. in its travel towards saidfixed element for operating the bypass to vary the quantity of fluidbypassed and thereby regulate the rate of advancement of platen towardssaid element accordance with intermediate successive positions of theplaten.

9. In a drawing a fixed die holding element, a platen mounted formovement toward and from said element, ram means connected to saidplaten for operating it toward and from said element, a source ofactuating fluid, a continuously operating a circuit including saidsource, said pump and said ram means for causing operation of said rammeans in one direction or the other, a bypass forming a part of saidcircuit and operable to bypass a portion of said actuating fluid beingdelivered by said pump to said ram means around said ram means whilesaid ram means is operating the platen towards said fixed element, a campart and a follower part, one of said parts being mounted on the platenfor travel therewith and the other part being positioned adjacentthereto for operation from the other part during the travel of theplaten, and means controlled by said other part for operating saidbypass to vary the quantity of fluid bypassed and thereby control thespeed of travel of the platen as determined by said cam part, during thetravel of said platen towards said fixed element.

10. In a drawing press, a fixed die holding element a platen mounted forniovement toward and from said element, means for confining a blankagainst said fixed element, means for actuati g said platen toward andfrom said element. means for pressing said blank confining memberagainst said element, cam means operated by said platen in its vementtoward said element for varying the speed of travel of said platenthrough intermediate zones of travel while in contact with said ble. andcam means also operated by said platen ror concomitantly varying thepressure of said blank confining member against said element.

11. In a drawing press, a fixed die holding element, a platen mountedfor movement toward and from said element, means for actuating saidplate-n toward and from said element, a member for holding a blankagainst said element, a fluid circuit including fluid actuated means forpresssaid blank holding member against said element, a pressure releasevalve included in said circuit for bypassing the fluid that presses saidmember against said'element Whenever the pressure exceeds the setting ofsaid release valve, and means controlled by said platen for varying thesetting of said pressure release valve at an intermediate point in thetravel of said platen toward element while in contact with said blank.

12. In drawing press, a fixed die holding eloincnt, a platen mounted formovement toward and from said element, means for actuating said platentoward and from said element, a member for holding a blank against saidelement, a fiuid circuit including fluid actuated means for pressingsaid blank holding member against said element, a pressure opened butspring closed valve forking a part of said circuit, and opened by thefluid pressure which confines said member to said element, and meanscontrolled by said'platen for changing the pressure on said spring at anintermediate point in the travel of said platen toward said element.

13. In a drawing press or the like, a relatively fixed die holdingelement, a platen mounted for movement toward and from said element, ablank holding member also movable toward and from said element, meansincluding a variable delivery pump anda iluid circuit including saidpump for actuating said platen toward and from said element, meansincluding a cam device operated by the travel of said platen for varyingthe delivery of said pump and thereby varying the rate of travel of saidplaten in accordance with a predetermined plan represented by said camdevice and its relation to said platen, means including a variabledelivery pump and a fluid circuit ineluding said pump for actuating saidblank hold;

ing member toward and from said element, said second pump havingpressure responsive means for an Jomatically set-ting it toapproximately neu tral delivery condition when the pressure at thedelivery side of said second pump exceeds a predetermined pressure andadjustable for varying the pressure at which it sets itself toapproximately neutral delivery condition, and means operable in apredetermined speed ratio to the travel of said platen and concurrentlytherewith for varying the pressure regulating means in a manner to varythe pressure at which said second pump will set itself to approximatelyneutral delivery position, in accordance with a sequence having adefinite predetermined relation to the successive positions of theplaten.

14. In a drawing press, a relatively fixed die holding element having anunyielding blank clamping a platen mounted for movement toward and fromsaid element, hydraulic means for actuating said platen toward and fromsaid element, a member for holding a blankagainst said unyielding areaon said element, additional separate hydraulic means for exertingindependen y of the platen travel a holding pressure on member, andmeans responsive to the successive positions of the platen in itsmovement toward said element for partially but not fully releasing thehydraulic holding pressure of said member on said blank when said platenreaches a predetermined, critical drawing position, intermediate of thestart and finish of the drawing operation.

15. In a drawing press, a relatively fixed die holding element having aclamping area rigid with the remainder of the die, a platen mounted formovement toward and from said element, means for actuating said platentoward and from said element, a member for holding a blank against saidclamping area of element, hydraulic means for exerting a holdingpressure on said member independently of the platen travel, a source ofliquid under pressure connected to said hydraulic means to supply theholding ressure thereto, and means including cam device operatedconciurently with said platen toward said element for decreasing andincreasing the delivery of liquid from said source to said hydraulicmeans and hence decreasing and increasing the pressure of said holdingmember against said element selectively in a predeterm ned sequence ofpressures bearing a definite timed re" laticn to successive positions ofsaid platen in its travel toward said fixed element.

16. In a drawing press, a relatively fixed die holding element, a platenmounted for movement toward and from said element, means for actuatingsaid platen toward and from said ele-' ment, a member for holding ablank against said element, a fluid actuated device for exerting aholding pressure on said member, means for deliering a holding fiuidunder pressure to said device, pressure responsive means for releasingthe fluid delivered to said device when a predetermined pressure hasbeen reached, and means responsive to the travel of said platen towardsaid element for adjusting said pressure responsive means in a manner tovary the quantity of fluid delivered to said device in differentsuccessive positions of said platen in its travel toward said element.

17. In a drawing press, a relatively fixed die holding element, a platenmounted for movement toward and from said element, means for actuatingsaid platen toward and from said element, a member for holding a blankagainst said element, a fluid actuated device for exerting a hold ingpressure on said member, means for delivering aholding fluid underpressure to said device, a pressure opened valve connected to saiddevice for releasing the fluid pressure thereon when a predeterminedpressure on said member has been reached, and means responsive to thetravel of said platen towards said element for adjusting the pressure atwhich said valve opens at a plurality of different successive positionsof said platen in its travel towards said element.

18. In a drawing press, a pair of relatively movable drawing dies, ablank holding member for clamping a blank against one of said dies,fluid pressiu'e actuated means for holding said member in blank clampingposition exerting a clamping pressure on a portion of a clamped blankindependently of the relative movement of the dies, means independent ofthe pressure of the dies on the blank for delivering a fiuid underpressure to said holding means for furnishing the holding pressure andmeans controlled by the relative movement of said dies during a drawingoperation for increasing and decreasing the fluid pressure on saidholding means in accordance with a predetermined plan determined by therelative positions of the dies.

19. In a drawing press, a pair of relatively movable drawing dies, ablank holding member for clamping a blank against one of said dies,fluid pressure actuated means for holding said memher in blank clampingposition and exerting a clamping pressure on a portion of a clampedblank independently of the relative movement of the dies, meansindependent of the pressure of the dies on the blank for delivering afluid under pressure to said holding means for furnishing the holdingpressure and means controlled by the relative movement of said diesduring a drawing operation for releasing fluid from and adding fluid tosaid holding means in accordance with a predetermined plan, whereby theholding pressure on a blank being drawn will be decreased and increasedin a definite relation to the relative positions of the dies.

THOMAS F. STACY.

